What is the best first sentence you can think of off the top of your head?

Would it be cheating if I have memorised the opening line of the story I am yet to publish? Perhaps if today's topic had of included a prompt to use that would have been more helpful. But seeing as this opening sentence is my own, and at the time it was the best that I could come up with, I will use it. It comes from the Prologue (Titled Goodbye) of my novel, The Other Half of Life and it is as follows:

"You are the only one who understands me."

I wrote my story for NaNoWriMo in November of last year. It was the first time I had taken part. The challenge is to write 50,000 in one month. I have always wanted to write a book and so I thought this would be a really fun way to get it written. Looking back, almost 9 months later, I realise it was fun, but at the time it was very hard work and quite stressful. But I have my 50,005 words and now I'm in the process of editing. Hopefully one day it will be published.

The basic backstory was developed when I was 15 years old. I had written what is essentially my prologue as a creative writing piece for my English class when I was in 11th grade. My teacher was a bit concerned with how I had come up with such dark material, but she told me that it was very good work. I wrote the story without planning, it just flowed from me the night before the assessment was due. I wanted my story to reflected Edgar Allan Poe's philosophy that a story should end at the climax (and not have a resolution as such). I had also heard that writing in the second person singular (that is, you) was very rare, and hardly used. So that's what I set out to do, write a short creative piece using you as the subject and wrapping up the story in such a way that the climax came at the very last sentence.

The opening sentence is not referring to a person, but an object the main character has personified in her despair and loneliness. There are hints throughout the prologue as to who (or what) the girl's audience actually is, but hopefully it is done subtly enough so as to not lose dramatic impact when the reader comes across the final sentence of the prologue.

Knowing that this is a dark tale, that the main character is melancholic and the opening line is "You are the only one who understands me." Who/ what do you think this sentence is referring to? Post your ideas in the comments below, they are most welcome :)